432. All O`one Data Structure LeetCode Solution | Easy Approach

Minimum Cost to Merge Stones

All O`one Data Structure Design a data structure to store the strings’ count with the ability to return the strings with minimum and maximum counts.

Implement the AllOne class:

  • AllOne() Initializes the object of the data structure.
  • inc(String key) Increments the count of the string key by 1. If key does not exist in the data structure, insert it with count 1.
  • dec(String key) Decrements the count of the string key by 1. If the count of key is 0 after the decrement, remove it from the data structure. It is guaranteed that key exists in the data structure before the decrement.
  • getMaxKey() Returns one of the keys with the maximal count. If no element exists, return an empty string "".
  • getMinKey() Returns one of the keys with the minimum count. If no element exists, return an empty string "".

Example 1:

["AllOne", "inc", "inc", "getMaxKey", "getMinKey", "inc", "getMaxKey", "getMinKey"]
[[], ["hello"], ["hello"], [], [], ["leet"], [], []]
[null, null, null, “hello”, “hello”, null, “hello”, “leet”]

Explanation AllOne allOne = new AllOne(); allOne.inc(“hello”); allOne.inc(“hello”); allOne.getMaxKey(); // return “hello” allOne.getMinKey(); // return “hello” allOne.inc(“leet”); allOne.getMaxKey(); // return “hello” allOne.getMinKey(); // return “leet”


  • 1 <= key.length <= 10
  • key consists of lowercase English letters.
  • It is guaranteed that for each call to deckey is existing in the data structure.
  • At most 5 * 104 calls will be made to incdecgetMaxKey, and getMinKey.

All O`one Data Structure Solutions

Time: O(n)
Space: O(n)


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